Sigmoid colon cancer occasionally attaches to the adjacent viscera. It is estimated that such attachment occurs in 6% to 12% of all patients with colon carcinoma without distant metastases. This study was performed to identify the parameters to distinguish direct tumor invasion to adjacent organs from simple inflammatory adhesion in sigmoid colon cancer and to clarify the difference of survival and recurrence pattern between two groups. METHODS: Between 1989 and 1998, 415 patients underwent resection of sigmoid colon cancer in our clinic. Of these, 46 had tumors adherent to adjacent organs and confirmed as tumor direct invasion or simple inflammatory adhesion by pathologic examination. The mean age of 46 cases was 54.2+/-12.8 (mean+/-SD) years and median follow up was 21 (3~53) months. RESULTS: Among the clinical and pathologic parameters such as symptoms and laboratory findings presenting bowel obstruction, serum CEA levels, preoperative radiological findings, tumor size, differentiation, and stage, there was no specific one that was correlated with direct tumor invasion or inflammatory adhesion. Almost all cases with adhesion to adjacent organ were treated by an en bloc resection including mutivisceral resection. The group with direct invasion had inferior disease free survival rate and overall survival rate comparing with simple inflammatory adhesion group. CONCLUSIONS: In the situation that there was no valuable parameter suggesting direct tumor invasion, en bloc resection or multivisceral resection involving one tumor-free plane may be beneficial to the patients with sigmoid colon cancer adherent to adjacent organ.